The discussion throughout this specification comes about due to the realisation of the inventor and/or the identification of certain prior art problems by the inventor.
The on-site treatment and disposal of commercial and domestic sewage and other wastewater such as storm water has been prohibited in many areas due to shallow or non absorptive soils and other site limitations such as high water tables, shallow rock and high rainfall. These conditions have prevented the use of conventional ground absorption trenches and evapotranspiration systems. The inability to effectively treat and dispose of wastewater on-site has restricted development to those areas that are serviced by conventional sewerage systems. However it is clearly evident that recent natural disaster events throughout the world such as earthquakes, hurricanes, tsunamis and the like have dramatically shown that even areas serviced by conventional off-site sewage systems require on-site treatment and disposal of waste water from time to time.
In the past the problems associated with on-site disposal techniques such as non-absorbent soils, high water tables and large volumes (site limitations) have not been effectively solved. The inventor has realised that an issue to be addressed is determining how can the treatment mechanisms that enable the on-site systems to operate be protected from the affects of site limitations.
One attempt at alleviating the limitations noted above comprises the installation of pump-out septic systems that consist of large wastewater holding tanks that collect all wastewater for removal off site by road tankers for transport to sewerage treatment plants. This however, is quite inefficient and unwieldy.
The early 1980's saw the introduction of the Aerated Wastewater-treatment System (AWTS) in Tasmania and a number of Australian mainland states. AWTS were originally designed to fit into large wastewater holding tanks. AWTS produced chlorinated wastewater that was approved for surface disposal onto prescribed garden beds. AWTS solved the high cost associated with the use of pump out road tankers however, other problems with the wide spread use of AWTS became apparent. These include the AWTS' need for frequent expert maintenance, increasing purchase and running costs and a serious health concern related to the surface disposal of chlorine treated sewage near houses that are a source for communicable diseases. AWTS require an additional irrigation area of several hundred square metres to evaporate or absorb the AWTS treated effluent. The size of the AWTS is dependant on climatic and soil factors with cooler regions generally requiring larger areas.
Any discussion of documents, devices, acts or knowledge in this specification is included to explain the context of the invention. It should not be taken as an admission that any of the material forms a part of the prior art base or the common general knowledge in the relevant art in Australia or elsewhere on or before the priority date of the disclosure and claims herein.
An earlier device created by the inventor was the Field Septic Disposal System, which is the subject of an Australian Standard Patent, dated 29 Jan. 1991, Number PK4340. This device forms the basis for the primary stage of the present invention.